Injury is a significant cause of overall morbidity and mortality and the leading cause of death among children and young adults. Alcohol's contribution to traffic injuries is well documented and there is compelling evidence that drinking also plays a causal role in a substantial proportion of other unintentional and intentional injury events. Although the federal alcohol limit of BAC 0.04 for operation of commercial vessels has been in force for almost a decade, the effects of this level on ship handling performance have not been evaluated. Thus, we propose to measure whether or not significant decrements in performance are evidence at the current legal limit. Moreover, the true contribution of alcohol to injury may be underestimated because most studies of the risks of drinking for injury focus on acute exposure to alcohol. In contrast, the proposed study will also examine the risks of residual (hangover) effects of alcohol exposure on ship handling performance the day following intoxication. We have selected simulated commercial ship handling as a measure of performance for several reasons; (a) sophisticated equipment is available to simulate ship handling performance; (b) public policy regulates the use of alcohol in conjunction with a number of types of public and private transport; and (c) little research has been done on alcohol's effects on commercial ship handling. We will conduct two randomized studies to assess the acute effects of 0.04 gm% BAC and hangover effects after 0.10 gm% BAC on stimulated ship guidance using both relatively inexperienced maritime cadets and experienced ship officers. The results of this study will provide information on the risks of hangovers for injury and may inform public policy on alcohol use in conjunction with commercial ship operation.